Drug & supplement interaction

Quercetin + Ceftazidime

Ceftazidime brand names: Ceftazidime, Fortaz, Tazidime, Ceptaz, Tazicef.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Ceftazidime falls into 2 drug categories that Quercetin can interact with; the most serious is rated moderate. Theoretically, concomitant use might increase the effects and adverse effects of OAT3 substrates.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions2
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Quercetin and Ceftazidime

These two interact in 2 distinct ways. Each one is explained separately below.

Why Are There 2 Interactions?

Quercetin interacts with whole categories of medication. Ceftazidime falls into 2 of those categories, so it can interact with Quercetin in 2 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

ORGANIC ANION TRANSPORTER 3 (OAT3) SUBSTRATES

1 of 2

Why this applies to Ceftazidime

Ceftazidime falls under ORGANIC ANION TRANSPORTER 3 (OAT3) SUBSTRATES — the group Quercetin interacts with.

Theoretically, concomitant use might increase the effects and adverse effects of OAT3 substrates.

In vitro research shows that quercetin is a strong non-competitive inhibitor of OAT3, with half-maximal inhibitory concentration (IC50) values as low as 0.75 mcM. So far, this interaction has not been reported in humans.
Severity Moderate Likelihood Possible Evidence D

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the short version on quercetin and ceftazidime. Your kidneys use a little protein called OAT3 to move ceftazidime out of your blood and into your urine. In test-tube studies, quercetin blocks that transporter. If it did the same thing in people, your body might clear ceftazidime a bit more slowly, leaving a little more of it hanging around. That could nudge up side effects you'd expect from this antibiotic, like upset stomach, diarrhea, or rash.

I want to be honest about the strength of this: it's only theoretical, based on lab data, and it has never actually been reported in real patients. Since ceftazidime is given by injection in a hospital or clinic, your care team is watching you closely. Still, it's worth mentioning your quercetin supplement to your pharmacist or doctor so they have the full picture.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Li C, Wang X, Bi Y, et al. Potent Inhibitors of Organic Anion Transporters 1 and 3 From Natural Compounds and Their Protective Effect on Aristolochic Acid Nephropathy. Toxicol Sci. 2020;175(2):279-291. PubMed
  2. Ni Y, Duan Z, Zhou D, et al. Identification of Structural Features for the Inhibition of OAT3-Mediated Uptake of Enalaprilat by Selected Drugs and Flavonoids. Front Pharmacol. 2020;11:802. PubMed
Moderate

ORGANIC ANION TRANSPORTER 1 (OAT1) SUBSTRATES

2 of 2

Ceftazidime also falls under ORGANIC ANION TRANSPORTER 1 (OAT1) SUBSTRATES.

Theoretically, concomitant use might increase the effects and adverse effects of OAT1 substrates.

In vitro research shows that quercetin is a strong non-competitive inhibitor of OAT1, with half-maximal inhibitory concentration (IC50) values less than 10 mcM. So far, this interaction has not been reported in humans.
Severity Moderate Likelihood Possible Evidence D

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the gist for ceftazidime: your kidneys clear this antibiotic out of your body partly through a transporter called OAT1. In test-tube studies, quercetin blocks that transporter. If that same effect happened in people, ceftazidime could leave your system a little more slowly and build up, which in theory could mean a higher chance of side effects like nausea, diarrhea, or irritation where the drug is given.

I want to be honest about the strength of this, though. It's based only on lab research and has not been seen in real patients. Everyday food amounts of quercetin (apples, onions, tea) are very unlikely to matter. If you're getting ceftazidime and take high-dose quercetin supplements, just mention it to your pharmacist or doctor so they can keep an eye on things.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Ni Y, Duan Z, Zhou D, et al. Identification of Structural Features for the Inhibition of OAT3-Mediated Uptake of Enalaprilat by Selected Drugs and Flavonoids. Front Pharmacol. 2020;11:802. PubMed

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Quercetin Also Interacts With Other Medications

Quercetin has 1,168 moderate known drug interactions in our database — the Ceftazidime one above is among them. If you take anything else, check it against the full list below.

Moderate 1,168 No known interaction 1,662 (incl. Ceftazidime)
Taking anything else?

Check Another of Your Medications Against Quercetin

Covers the 2,830 medications we’ve checked against Quercetin. Pick one to open its full report.

Everything else you take

See Every Supplement That Interacts With Ceftazidime

This page covers Quercetin only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Ceftazidime page lists 37 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: African Wild Potato (moderate), Bacillus Coagulans (moderate), Bacillus Subtilis (moderate), Banderol (moderate) and Bifidobacterium Animalis Subsp. Lactis (moderate).

By severity: 36 moderate · 1 minor.

From our pharmacist’s overview on the Ceftazidime page

“A course of ceftazidime, an injectable antibiotic for serious infections, often comes with a probiotic to steady the gut, and that pairing is most of this list. Twenty-seven of the 37 ingredients on file are probiotics or fermented milk products whose live organisms the antibiotic can kill, blunting the supplement rather than the drug.”

Reviewed by 2 · Jul 18, 2026

Open the Ceftazidime interaction page

One more smart check

Taking Quercetin as Part of a Dietary Supplement Product? Check It for Interactions

We hold 4,589 real supplement products containing Quercetin, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Quercetin. Your product may carry other ingredients that interact with Ceftazidime too, on top of Quercetin — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Quercetin and Ceftazidime Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Quercetin
Top 5%

#48 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Ceftazidime
Steady interest

#1,793 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Quercetin

What is Quercetin?

Quercetin
  • Seasonal allergies
  • Antioxidant support
  • Heart and blood pressure health
  • Anti-inflammatory support
  • Immune support
  • Exercise recovery

Quercetin is a plant flavonoid with antioxidant and anti-inflammatory properties found in many common foods and sold as a supplement. While early research is interesting for allergies, blood pressure, and inflammation, strong human evidence is limited for most uses. It is generally well tolerated in food amounts, but talk to your pharmacist or doctor before taking high-dose supplements.

Read the full Quercetin monograph & all interactions
Medication

About Ceftazidime Injection

What Is Ceftazidime Injection Used For?

Brand names: Ceftazidime, Fortaz, Tazidime, Ceptaz, Tazicef

Ceftazidime injection is used to treat infections caused by susceptible bacteria in several parts of the body. These include lower respiratory tract infections (including pneumonia), urinary tract infections (both simple and complicated), skin and skin-structure infections, bone and joint infections, gynecologic infections, intra-abdominal infections (including peritonitis), bacterial septicemia (bloodstream infection), and central nervous system infections including meningitis.

Tazicef (ceftazidime for injection, USP) may be used on its own for confirmed or suspected sepsis, or combined with other antibiotics such as aminoglycosides, vancomycin, or clindamycin for severe or life-threatening infections and in patients with weakened immune systems. Treatment is intended only for infections proven or strongly suspected to be caused by bacteria that respond to ceftazidime.

See full Ceftazidime Injection drug information
Keep checking

Other Drugs & Quercetin

Browse every other medication we’ve checked against Quercetin — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
1,168Moderate
0Minor
1,661No known interaction
1,168 Moderate 1,661 No interaction
Moderate

1,168 interactions

Showing 60 of 1,168 moderate interactions — see all 1,168 on the Quercetin page.

No interaction 1,661 drugs checked — show the list

We also checked Quercetin against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 1,661 medications checked with no known interaction — see the full Quercetin list.

See the full Quercetin interactions page
See every supplement checked against Ceftazidime, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Quercetin monograph › Uses, safety, and every drug interaction in one place Ceftazidime supplement interactions › Every supplement checked against Ceftazidime, ranked by severity Ceftazidime Injection drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Quercetin and Ceftazidime Together: Common Questions

Can you take Quercetin with Ceftazidime?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
Why are there 2 interactions listed for Quercetin and Ceftazidime?
Ceftazidime belongs to more than one drug category, and Quercetin interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the Quercetin and Ceftazidime interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Ceftazidime and Quercetin?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.